This invention relates to a gear-type rotary speed changer, and more particularly to the type of speed changer having a planetary gear set. Even more particularly, this invention relates to a speed changer having compound planocentric gear drives and an orthogonally arranged planetary gear set.
It is well known to one skilled in the art that a planetary gear set may be utilized for transmitting rotational torque in speed changing devices. Heretofore, it has also been customary to utilize cycloidal gear sets in speed changing devices such as those disclosed in U.S. Pat. Nos. 3,129,611, 4,297,920, 4,884,473 and 4,898,065. Of these previously disclosed speed changing devices, only two have coupled the cycloidal gear with a planetary gear set. Each of these speed changing devices, U.S. Pat. Nos. 3,129,611 and 4,898,065, have the cycloidal gear set connected to the planetary gear set by means of eccentric shaft structures.
However, as disclosed herein, the speed changer according to this invention maintains a compound planocentric gear set in a balanced, constant toothed engagement with the planetary gear set. This arrangement reduces the amount of wear that normally affects the gear teeth, and therefore the lifetime of the device itself. Also, prior such speed changing devices, although capable of high speed reduction ratios, were often limited by the number of speed reduction ratios capable of being created by a single device.
It is therefore an object of this invention to provide a compound planocentric cycloidal speed changer having multiple reduction ratios, including high speed reduction ratios.
It is also an object of this invention to provide a speed changer that is constantly well balanced and thus less susceptible to wear.
Another object of this invention is to provide a speed changer which is compact with respect to its load bearing capabilities.
Still other objects of this invention will become apparent to those skilled in the art when the preferred embodiments are considered in conjunction with the accompanying drawings and the appended claims.